1. Field of the Invention
The present invention relates generally to an automatic method for ascertaining the volatile contents of coal samples. More particularly, this invention relates to a multiple sample precise method for accurately and automatically determining the volatile content of multiple coal or coke samples in sequence.
2. Description of Related Art
Coal is the most plentiful fuel in the fossil family. The use of coal increased dramatically in the 18th century as the steam engine evolved and later as the use of electricity became common. Today the primary use of coal is to produce electrical energy. Coal is mined throughout many parts of the world; and thus, varied in its composition as mined. Since there are a wide variety of coals mined in different parts of the world, a coal may have a range of properties that differs from others, especially coals from diverse regions. A major factor in determining coal quality is coal rank. Coals ranked from lowest (brown coal) to highest (anthracite). The coal quality is determined by the amount of fixed carbon volatiles in the coal.
When coal is used in a power plant it is important to know the heat value of a coal by determining thermal weight losses due to the formation of volatile matter. Coal contains more than 50% by weight of carbon, and in high grade bituminous coal fixed carbon is 75-90%. The remainder is volatile matter which refers to other constituents of coal except moisture which are liberated at high temperatures. Volatile matter includes the products given off by a material as gas or vapor determined by prescribed methods, which determine the properties of coal.
A typical method of determining the volatiles in coal is through thermogravimetric analysis. In thermogravimetric analysis the mass of a sample in a rigidly controlled atmosphere is recorded as a function of temperature or time, or both. Each sample is subjected to a predetermined temperature and time and the measured weight loss determines the volatile matter content. Various methods for determining the volatile content through thermogravimetric analysis have been used. One method is ASTM standard designation D3175-11. D3175-11 it is manual method and its use is complex and slow. The precision of the results from using D3175-11 leaves a bias as to their accuracy as well as a desire to have a multiple sample analysis of coal samples. The manipulation is extensive and prone to errors. D3175-11 has the advantage that if done carefully and properly, results can be reproduced because the samples are always in same context, introduced in a hot furnace, other multiple sample ASTM method like D7582-10 ramps the furnace temperature from a lower temperature to temperature of 900-950 C. does not have the desired reproducibility because it is impossible to take the weights of all sample holders simultaneously to weight exactly at 7 minutes inside the furnace at furnace temperature of 950 C. for ASTM other temperatures for other standards as is required.